A mains electricity (AC-powered) device assembly used during endoscopic procedures of the uterus (i.e., hysteroscopy) to distend (expand by pressure) the uterus by filling the uterine cavity with a pressure-limited gas [typically carbon dioxide (CO2)] providing the operator with a space in which to carry out an examination or surgical intervention. Electronics assist in monitoring the pressure and maintaining the gas-filled space by compensating for gas leakage. This device may also be referred to as a gas distention system.